Golf club head with textured striking face

ABSTRACT

A golf club head includes a heel portion, a toe portion, a hosel, and a striking face. The striking face includes a plurality of scorelines each having an average depth no less than about 0.10 mm, a plurality of first micro-grooves each having an average depth no greater than about 0.010 mm, and a plurality of second micro-grooves overlaid on the first micro-grooves, each of the second micro-grooves having an average depth greater than the average depth of the first micro-grooves. Some embodiments can also have a plurality of textured surface treatment regions superimposed on the overlaid first and second micro-grooves so as to at least partially intersect the micro-grooves.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/482,896, filed Sep. 10, 2014 (now U.S. Pat. No. 9,308,422, issuedApr. 12, 2016), which is a continuation application of U.S. patentapplication Ser. No. 14/174,671, filed Feb. 6, 2014 (now U.S. Pat. No.8,858,361, issued Oct. 14, 2014), which is a continuation-in-part ofU.S. patent application Ser. No. 13/829,238, filed on Mar. 14, 2013 (nowU.S. Pat. No. 8,979,670, issued Mar. 17, 2015), which claims thebenefit, under 35 U.S.C. §119(e), of U.S. Provisional Patent ApplicationNo. 61/754,302, filed on Jan. 18, 2013. The subject matter of each ofthe priority applications is incorporated herein by reference in itsentirety.

BACKGROUND

This disclosure relates generally to the field of golf clubs. Moreparticularly, it relates to a golf club head with a textured strikingface for imparting greater spin to a golf ball when the golf ball isstruck.

A common goal of golf club head design, specifically for iron-type andutility-type club heads, and particularly for wedges, is to create astriking face for the club head that imparts significant spin to astruck ball. The striking face of such a club head typically has aplurality of parallel horizontal grooves or score lines. These scorelines assist in imparting spin at least by channeling water and debris,and by increasing the friction between the striking face and the surfaceof the ball. The spin-imparting qualities provided by such score linesare limited, however, by United States Golf Association (“USGA” herein)regulations governing score line geometry (and similar regulations ofother international golf equipment regulatory bodies). Moreover,conventional score lines fail to account for low-scale dynamicinteractions between the striking face and the ball.

Further improvements in the spin-imparting characteristics of club headstriking faces have included the provision of low-scale surface texturesin addition to, or in place of, the conventional score lines. Suchsurface textures, however, tend not to take into account the specificinteraction between a conventional elastomer-covered golf ball and ametallic striking face. Moreover, conventional surface texturing issubject to rapid wear, is often costly to produce, and may detract fromthe aesthetic quality of the club head. Furthermore, conventionalstriking face textures are generally ineffective at providing a highdegree of spin for each of the multitude of different types of golfshots that a golfer may attempt. For example, a ball hit with a clubhaving a conventional club head that is swung at a specific speed wouldhave different degrees of spin depending on whether the ball is squarelyaddressed by the club face or hit with an open club face. Otherconditions, such as moisture on the club face and/or the ball, andwhether the ball is struck with a full swing, half swing, or chip-typeswing of the club, can affect the degree of spin imparted to the ball.

The creation of spin, particularly back-spin, on a struck golf ball, islargely a function of the magnitude of the frictional contact or“traction” between the striking face of the club head and the ball onimpact. Where a high degree of back-spin is desired, as in higher numberirons and wedges, maximizing this traction factor is therefore a designgoal. Increased traction is generally associated with increased surfaceroughness of the striking face. Surface roughness is commonly expressedin terms of R_(a), defined as follows:

$R_{a} = {\frac{1}{n}{\sum_{i = 1}^{n}{y_{i}}}}$

where n is the number of sampling points and y is the deviation from amean line (at a given sampling point). As a practical matter, R_(a)represents the average of deviations from a mean line over a2-dimensional sample length of a surface.

Another surface roughness parameter is known as R_(t) (sometimesreferred to as R_(y)). This parameter represents the maximumpeak-to-trough distance in a given 2-dimensional sample length of asurface.

The regulations of the USGA limit the surface roughness of the strikingface of golf clubs generally to a degree of roughness no greater thanthat imparted by sand-blasting or fine milling. In practical terms, thisstandard has been interpreted to mean a surface having a value of R_(a)no greater than 0.0046 mm (180 μin.), and a value of R_(t) of no morethan 0.025 mm (1000 μin.). Thus, the need is evident to maximize thetraction between the club face and the struck ball without exceeding theroughness maximum established by USGA rules.

Accordingly, a textured striking face for a golf club head has beensought that imparts a high degree of spin to the ball for a wide varietyof golf shots under a wide variety of conditions, that has good wearcharacteristics, that complies with USGA rules, and that enhances (or atleast does not detract from) the aesthetic qualities of the club head.

SUMMARY

In accordance with one embodiment, a golf club head is provided having aheel portion, a toe portion opposite the heel portion, a hosel adaptedto receive a shaft, a striking face, and a rear surface opposite thestriking face. The striking face can include a plurality of score linesthat have an average depth no less than about 0.10 mm. The striking facecan also have a first micro-groove pattern and a second micro-groovepattern overlaid on the first micro-groove pattern. The firstmicro-groove pattern has a plurality of arcuate first micro-grooves thatare parallel to one another, each of the first micro-grooves having afirst average depth no greater than about 0.025 mm and a first averagewidth no greater than about 0.51 mm. The second micro-groove pattern hasa plurality of second micro-grooves that are parallel to one another,each of the second micro-grooves having a second average depth nogreater than about 0.025 mm and a second average width different thanthe first average width.

In some such embodiments the second average depth is greater than thefirst average depth, and in some embodiments is a whole number multipleof the first average width.

In other embodiments the second arcuate micro-grooves are substantiallyparallel to the first arcuate micro-grooves.

Other embodiments can additionally comprise a third micro-groove patterncomprising a plurality of arcuate third micro-grooves that are parallelto one another. Each of the third micro-grooves can have a third averagedepth no less than the second average depth and a third average width noless than the second average width.

In some such embodiments the third micro-grooves are not parallel to atleast one of the first and second micro-grooves.

In further embodiments the striking face additionally comprises aplurality of surface treatment regions overlaid onto the first andsecond micro-groove patterns. The plurality of surface treatment regionscan comprise heat-treated regions. The plurality of surface treatmentregions can also or instead comprise laser etched regions. In someembodiments, each of the surface treatment regions extends along agenerally linear path.

Another embodiment provides a golf club head comprising a heel portion,a toe portion opposite the heel portion, a hosel adapted to receive ashaft, a striking face, and a rear surface opposite the striking face.The striking face can include a plurality of score lines each having anaverage depth no less than about 0.10 mm, a first micro-groove patternand a second micro-groove pattern overlaid on the first micro-groovepattern. The first micro-groove pattern comprises a plurality ofparallel arcuate first micro-grooves, each of the first micro-grooveshaving a first cross-sectional profile that defines a first averagedepth no greater than about 0.025 mm and a first average width nogreater than about 0.51 mm, and following a first arcuate path thatcurves about a first center of curvature. The second micro-groovepattern comprises a plurality of parallel arcuate second micro-grooves,each of the second micro-grooves having a second cross-sectional profilethat defines a second average depth no greater than about 0.025 mm and asecond average width no greater than about 0.51 mm, and following asecond arcuate path that curves about a second center of curvature. Oneor more of the second average depth, second average width and secondcenter of curvature are different than respective ones of the firstaverage depth, first average width and first center of curvature.

In some such embodiments the golf club head has a virtual ground planewhen the golf club head is in a reference position, and the first centerof curvature is below the virtual ground plane. In additionalembodiments the second center of curvature is also below the virtualground plane. But in further embodiments the second center of curvatureis above the virtual ground plane.

In further embodiments aligned first ends of the score lines, proximatethe heel, define a first virtual vertical plane and aligned second endsof the score lines, proximate the toe, define a second virtual verticalplane, and the first center of curvature is between the first and secondvirtual vertical planes. In some such embodiments the second center ofcurvature is above the virtual ground plane and between the first andsecond virtual vertical planes.

In yet additional embodiments the second center of curvature is offset180° from the first center of curvature. But in some additionalembodiments the second center of curvature is aligned with the firstcenter of curvature.

Yet further embodiments can additionally comprise a third micro-groovepattern overlaid onto the first and second micro-groove patterns, thethird micro-groove pattern comprising a plurality of thirdmicro-grooves, each of the third micro-grooves having a third averagedepth no greater than about 0.025 mm, a third average width no greaterthan about 0.51 mm, and following a third arcuate path that curves abouta third center of curvature, the third arcuate grooves being parallel toone another. One or more of the third average depth, third average widthand third center of curvature is different than respective ones of thesecond average depth, second average width and second center ofcurvature.

In some such embodiments the third center of curvature is above thevirtual ground plane, and the third micro-grooves are not parallel tothe first or second micro-grooves.

In yet further embodiments a method of making a golf club head isprovided, comprising providing a club head main body including astriking face; and forming a first textured surface pattern in thestriking face, the first textured surface pattern imparting a surfaceroughness value to the striking face. Forming the first texture surfacepattern comprises forming a first micro-groove pattern and forming asecond micro-groove pattern superimposed on the first micro-groovepattern. Forming the first micro-groove pattern comprises forming aplurality of arcuate first micro-grooves that are parallel to oneanother, each of the first micro-grooves having a first average depth, afirst average width, and following a first arcuate path that curvesabout a first center of curvature. Forming the second micro-groovepattern comprises forming a plurality of arcuate second micro-groovesthat are parallel to one another, each of the second micro-grooveshaving a second average depth, a second average width, and following asecond arcuate path that curves about a second center of curvature. Oneor more of the second average depth, second average width and secondcenter of curvature are different than respective ones of the firstaverage depth, first average width and first center of curvature.

In some embodiments forming the first micro-groove pattern comprisesmechanically milling the first micro-grooves at a first milling depth,and milling at a first feed rate.

In further embodiments, forming the second micro-groove patterncomprises mechanically milling the second micro-grooves at a secondmilling depth, and milling at a second feed rate, wherein the secondmilling depth is deeper than the first milling depth and the second feedrate is greater than the first feed rate. In other embodiments, formingthe second micro-groove pattern comprises mechanically milling thesecond micro-grooves at a second milling depth, and milling at a secondfeed rate, wherein the second milling depth is deeper than the firstmilling depth and the second feed rate is greater than the first feedrate.

Other embodiments additionally comprise forming a third micro-groovepattern comprising a plurality of arcuate third micro-grooves that areparallel to one another, each of the third micro-grooves having a thirdaverage depth, a third average width, and following a third arcuate paththat curves about a third center of curvature, the third micro-groovepattern being superimposed on the first and second micro-groovepatterns, wherein the third center of curvature is different than thesecond center of curvature so that the third micro-grooves cross thesecond micro-grooves.

In some embodiments, forming the third micro-groove pattern comprisesmechanically milling the third micro-grooves at the second millingdepth.

Some embodiments additionally comprise forming a second textured surfacepattern superimposed on the first textured surface pattern in thestriking face so as to increase the surface roughness value of thestriking face. In some embodiments, forming the second textured surfacepattern includes laser etching the second textured surface pattern.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front perspective view of a golf club head, showing atextured striking face in accordance with an embodiment of thisdisclosure;

FIG. 2 is a front elevation view of the golf club head of FIG. 1;

FIG. 3 is a toe side elevation view of the golf club head of FIG. 1;

FIG. 4 is a cross-sectional view taken along plane 4-4 of FIG. 2;

FIG. 5 is detail view of a portion of the cross-sectional view of FIG.4;

FIG. 5A is a detail view of a portion of the cross-sectional view ofFIG. 5;

FIG. 6 is detail view of a portion of the cross-sectional view of FIG. 4according to another embodiment of this disclosure;

FIG. 7 is a detail view of a portion of the cross-sectional view of FIG.4 according to another embodiment of this disclosure;

FIG. 8 is a flow chart illustrating a method of forming a texturedstriking surface on a golf club head in accordance with an embodiment ofthis disclosure;

FIGS. 9-11 are front views of a portion of a golf club head with astriking face plane corresponding to the plane of the paper, that showthe steps of forming a spin-imparting textured striking face inaccordance with an embodiment of this disclosure;

FIG. 12 is detail view of a portion of the front view of FIG. 11;

FIG. 13 is a front view of another embodiment of a golf club head with astriking face plane corresponding to the plane of the paper, and inwhich the striking face has a second micro-groove pattern superimposedon a first micro-groove pattern;

FIG. 13A is another front view of the golf club head of FIG. 13;

FIG. 13B is a partial close up view of a portion of the striking face ofthe golf club head of FIG. 13A corresponding to the portion of thestriking face bounded by line 13B of FIG. 13A;

FIG. 13C shows a roughness curve of a portion of the striking face ofthe golf club head of FIG. 13 A moving across the striking face in adirection transverse to micro-grooves;

FIG. 13D is a front view of a golf club head according to one or moreembodiments herein;

FIG. 14 is a front view of yet another embodiment of a golf club headwith a striking face plane corresponding to the plane of the paper;

FIG. 15 is a front view of still another embodiment of a golf club headwith a striking face plane corresponding to the plane of the paper, andin which the striking face has a third micro-groove pattern superimposedon first and second micro-groove patterns;

FIG. 15A is another front view of the golf club head of FIG. 15;

FIG. 15B is a partial close up view of a portion of the striking face ofthe golf club head of FIG. 15A taken at line 15B of FIG. 15A;

FIG. 15C shows a cross section taken along line 15C-15C of FIG. 15B; and

FIG. 15D is a front view of a completed embodiment of a golf club head.

DETAILED DESCRIPTION

The drawings and their descriptions may indicate sizes, shapes andconfigurations of the various components. Such depictions anddescriptions should not be interpreted as limiting. Alternative sizes,shapes and configurations are also contemplated as within the scope ofthis disclosure.

Referring first to FIGS. 1 through 3, a golf club head 10 of theiron-type includes a heel portion 12, a toe portion 14 opposite the heelportion 12, a front portion 72, and a rear portion 70 opposite the frontportion 72. The golf club head 10 further includes a top portion 64 anda sole (bottom) portion 58 opposite the top portion 64. The heel portion12 further includes a hosel 52 extending therefrom for associating thegolf club head 10 with a shaft (not shown). The hosel 52 defines avirtual central hosel axis 54. The front portion 72 further includes astriking face 16, defined as the planar exterior surface portion of thefront portion 72 that generally conforms to a virtual striking faceplane 56 and is adapted to contact a golf ball at a factory-designatedloft angle LA (see FIG. 3). The striking face 16 is formed with surfacefeatures that increase traction between the striking face and a struckgolf ball, for both ensuring good contact with the ball (for example, inwet conditions), and imparting a degree of spin to the ball, e.g. forstability in flight. Included in these surface features is a grid ofsubstantially parallel horizontal grooves or score lines 18. The scorelines 18 and the other surface features will be described in detailbelow.

The golf club head 10 is preferably formed of a metal, e.g. titanium,steel, stainless steel, or alloys thereof. More preferably, the mainbody of the club head 10 is formed of 431 stainless steel or 8620stainless steel. In some embodiments, the main body of the club head isintegrally or unitarily formed, while in other embodiments, the mainbody is formed of plural components that are welded together orotherwise permanently associated with each other. For example, in someembodiments, the club head 10 is formed of a main body of a firstmaterial, and a striking wall (including the striking face 16) of asecond material different from the first, and welded to the main body.

Referring to FIGS. 2 and 3, the golf club head 10 is shown in a“reference position.” As used herein, “reference position” denotes aposition of a golf club head, e.g. golf club head 10, in which the soleportion 58 of the golf club head 10 contacts a virtual ground plane 50such that the hosel axis 54 of the hosel 52 lies in a virtual verticalhosel plane 66, which intersects the virtual striking face plane 56 toform a virtual horizontal line 62.

Referring specifically to FIGS. 2 and 3, a first virtual vertical plane74 is perpendicular to the striking face plane 56 and passes through theends of the score lines 18 proximate the toe portion 14. A secondvirtual vertical plane 76 is perpendicular to the striking face plane 56and passes through the ends of the score lines 18 proximate the heelportion 12. The region of the striking face 16 toe-ward of the firstvirtual plane 74 constitutes a toe region 78 of the striking face 16.The region of the striking face 16 heel-ward of the second virtual plane76 constitutes a heel region 86 of the striking face 16. The region ofthe striking face 16 between, and delimited by, the first and secondvirtual planes 74 and 76 constitutes a central region 68.

Referring specifically to FIG. 2, the striking face 16 further comprisesa face center 80. The face center 80 is located equidistant between thefirst virtual plane 74 and the second virtual plane 76. The face center80 is also equidistant between an uppermost point 82 of the strikingface 16 and a lowermost point 84 of the striking face 16.

In alternative embodiments, the golf club head 10 is of a type otherthan an iron-type as described above. Nonetheless, the type and,relatedly, the loft angle of the golf club head 10 are preferablyselected such that the effect of any imposed surface texture describedbelow, on ball trajectory, is desirable. For example, backspinproduction is generally a more desirable feature of high-loftediron-type clubs and wedges. As the golfer nears the pin, precision ingolf shots generally becomes more critical than other considerations,such as distance. As another example of desirability, the effect oftraction between a striking face and a golf ball is understood tocategorically differ between differently-lofted club heads. Golf balls,over the duration of contact with a club head having a relatively lowloft angle, have been observed to follow a retrograde motion, i.e., theytravel upwardly, change course, and return downwardly, resulting inforward spin. Golf balls, over the duration of contact with a club headhaving a relatively high loft angle, have been observed to travel onlyupwardly, resulting in backspin. Because of these considerations, thestriking face surface textures variously described below are preferablyapplied to a club head of a loft angle no less than about 15°, morepreferably no less than about 18°, and even more preferably no less thanabout 35° (e.g. a wedge-type golf club head).

As shown in FIGS. 1 and 2, the striking face 16 includes a gridcomprising a plurality of substantially horizontal score lines 18,typically formed by mechanical milling (e.g. spin-milling).Alternatively, in some embodiments, the score lines 18 are formed bystamping, casting, or other known method. The score lines 18 typicallyhave an average width no less than 0.1 mm, more preferably between about0.25 mm and 1.0 mm, and even more preferably, substantially equal toabout 0.90 mm. For all purposes herein, score line width is to bedetermined using the “30 degree method of measurement” (as described inAppendix II of the USGA Rules of Golf, Effective Jan. 1, 2012).Additionally, or alternatively, the score lines 18 have an average depthof no less than about 0.10 mm, more preferably between about 0.25 andabout 0.60 mm, and most preferably substantially equal to about 0.51 mm.The length and number of score lines 18, and the spacing between them,are generally selected as to conform to USGA regulations. For allpurposes herein, the “depth” of a score line, e.g. score lines 18, ismeasured from the general planar surface of the striking face 16, whichthus constitutes a datum plane. Additionally, or alternatively, thescore lines 18 each have a maximum width and a maximum depth within therespective ranges of average width and average depth discussed above.

The striking face 16 is also provided with a first textured surfacepattern 19 comprising a first plurality of very narrow, relativelyshallow grooves 20, which may be called “micro-grooves.” The firstplurality of micro-grooves 20, which may be formed by precisionmechanical milling (e.g., CNC milling), is advantageously formed as apattern of substantially parallel, arcuate lines intersecting the scorelines 18. One of ordinary skill in the art will appreciate that suchparallel arcuate grooves, when formed by a conventional milling process,will tend to slightly converge in the heelward and toeward directions.In the present disclosure such arcuate grooves are still consideredsubstantially parallel despite the slight convergence.

In the illustrated embodiments, each of the arcuate micro-grooves 20follows an arcuate path having a radius of curvature. As such, eacharcuate path is a portion of a circular arc, and the radius is takenfrom a center point of the circle, which can be termed a center ofcurvature. Thus, in this disclosure a center of curvature can be acenter point from which the radius of curvature of a particular arcuatepath is taken, so that the arcuate path curves about its center ofcurvature.

In the illustrated embodiment, preferably the radius of curvature ofeach arcuate micro-groove 20 is substantially the same. In someembodiments, the radius of curvature is between about 2-4 inches, andmore preferably is about 3 inches. As such, a center of curvature ofeach micro-groove would not be on the striking face 16. In theillustrated embodiment each of the arcuate micro-grooves 20 follows anarcuate path that is generally convex relative to the virtual groundplane 50. Such paths each have a center of curvature that is spaced fromthe striking face 16 and below the virtual ground plane 50. In someembodiments the micro-grooves can follow an arcuate path that isgenerally concave relative to the virtual ground plan 50. Such pathscould each have a center of curvature above the striking face 16. Instill other embodiments the micro-grooves could be tilted so as to beconcave or convex relative to, for example, the first virtual verticalplane 74.

It is to be understood that, in other embodiments, the arcuate paths ofthe micro-grooves 20 may not all have the same radius of curvature. Forexample, in some embodiments each of the micro-grooves may curve aboutthe same center. In still other embodiments, the arcuate paths of themicro-grooves may be generally parabolic.

The first textured surface pattern 19 formed by the micro-grooves 20preferably covers at least the central region 68 of the striking face,and preferably extends at least partly into the toe region 78. Morepreferably, the first textured surface pattern 19 extends at leastpartly into the toe region 78 and the heel region 86. Preferably, thefirst textured pattern extends toward the toe portion past the uppermostpoint 82 of the club head 10 (see FIG. 2). In some embodiments, thefirst textured pattern covers the majority, and in some cases theentirety, of the toe region 78 of the striking face 16. Alternatively,or in addition, the first textured surface pattern 19 covers theentirety of the striking face 16 of the club head 10.

The micro-grooves 20 preferably have an average depth (measured inaccordance with depth d as shown in FIG. 5A) no greater than 0.025 mm(1000 μin.), more preferably between 0.015 mm (600 μin.) and 0.025 mm(1000 μin.), and even more preferably between 0.020 mm (800 μin.) and0.025 mm (1000 μin.). Additionally, or alternatively, the micro-grooves20 preferably have an average width (measured in accordance with widthw₂ of FIG. 5A) of between 0.25 mm (0.010 in.) and 0.51 mm (0.020 in.),more preferably between 0.30 mm (0.012 in.) and 0.43 mm (0.017 in.). Thedimensions of the micro-grooves 20 and the spacing between them willhave a significant effect on the value of R_(a) of the striking face.Thus, these dimensional parameters must be selected so that the maximumpermitted value of R_(a) noted above is not exceeded. However, becauseof normal surface variation and machine tolerances, a sample pool ofclub heads having micro-grooves intended to effect a specific targetsurface roughness R_(a) value may likely effect surface roughness R_(a)values dispersed about a range. Consequently, as a practical matter, thefirst textured surface pattern is preferably selected to produce anaverage value of R_(a) close to, but still somewhat less than, thedesired optimal value of R_(a). Likewise, the first textured surfacepattern also produces a first value of R_(t), (which may be termed“R_(t1)”), that may advantageously be somewhat less than the desiredoptimum value of R_(t).

The striking face 16 is further provided with a second textured surfacepattern superimposed on the first textured surface pattern 19 at leastin the region of the striking face occupied by the score lines 18 (i.e.the central region 68). The second textured surface pattern isadvantageously provided by a series of textured or roughened regions,each of which is formed between an adjacent pair of score lines 18. Inthe illustrated exemplary embodiment, the textured or roughened regionsare formed as a plurality of interposed textured surface treatmentregions 22, with at least one, and preferably two or more, of theplurality of the textured surface treatment regions 22 formed betweeneach adjacent pair of score lines 18. The textured surface treatmentregions 22 are advantageously configured and formed as horizontal etchlines, as described in detail below. In some embodiments, as shown e.g.in FIG. 1, adjacent pairs of horizontal etch lines are coupled byvertical end lines.

Preferably, the club head 10 includes the textured surface treatmentregions 22 in a repetitive pattern having a surface density of four suchregions 22 extending horizontally between each pair of the score lines18. In alternative embodiments, the textured surface treatment regions22 are generally linear and extend obliquely, i.e. at an angle relativeto the ground plane 50 (e.g. between 5° and 25°, measured in thestriking face plane 56), when the club head 10 is in the referenceposition. In yet other embodiments, the textured surface treatmentregions 22 follow an arcuate path and/or an intermittent path. However,the textured surface treatment regions 22 preferably extendhorizontally, and in parallel relation to each other. Theseconfigurations and orientations aid a golfer in aligning the club head10 and avoid—in combination with the first textured surface pattern(e.g. the micro-grooves 20)—an interference pattern that may distract orirritate the golfer, thus negatively affecting performance. Preferably,the interposed textured surface treatment regions 22 are spaced from anyscore lines 18. This provides for maintained structural integrity of,and thus an enduring effect on performance by, the score lines 18.

An exemplary textured striking face configuration is shown in FIG. 4.The score lines 18, micro-grooves 20, and the textured surface treatmentregions 22 are not shown to scale, and the illustrated cross-sectionalshapes of these features are exemplary only. For example, the texturedsurface treatment regions 22 may have a generally U-shapedcross-section, as shown, or they may have an irregular cross-section,depending on the particular way they are formed, as described below. InFIG. 5A, each of the textured surface treatment regions 22 is shown ashaving a width W₁ and an irregular cross-section. However, inalternative embodiments, the textured surface treatment regions 22 aregenerally U-shaped in cross-section (see, e.g., FIGS. 5 and 6), and mayoptionally have raised edges (see, e.g., FIG. 7).

In any previously-described embodiment, each textured surface treatmentregion 22 is defined as a region of the striking face having texturalcharacteristics that contrast with the general texture of itssurrounding area, which texture generally corresponds to the process bywhich it is formed. In addition, preferably, each textured surfacetreatment region also constitutes a coterminous region that is visuallydistinct from its surrounding area, such as, for example, having adistinct color, light reflectance property, or other visual quality.

The textured surface treatment regions 22 are preferably of a scale lessthan that of the score lines 18, to ensure that the configuration of thestriking face 16 conforms to USGA regulations. For example, the texturedsurface treatment regions 22 preferably each have an average width(measured in accordance with w₁ of FIG. 5A) no less than 0.01 mm, morepreferably no less than 0.10 mm, and even more preferably between about0.10 mm and about 1.0 mm. Additionally, or alternatively, the texturedsurface treatment regions 22 include a maximum width of a value similarto the values described with regard to average width.

Superimposing the second textured surface pattern on the first texturedsurface pattern 19 increases the value of R_(t) of the striking face 16from R_(t1) to a higher value (R_(t2)). Therefore, the dimensions of thetextured surface treatment regions 22 of the second textured surfacepattern should be selected so that R_(t2) does not exceed theabove-noted maximum permitted value of R_(t).

The textured surface treatment regions 22 of the second textured surfacepattern may be mechanically milled, but, as described below, in apreferred embodiment, they are laser-etched into the striking face 16.One advantage of laser etching is believed to be that the surfacetexture created by the removal of metal (e.g. by vaporization and/or bysloughing off micro-flakes) by the laser in forming the textured surfacetreatment regions 22 provides a particularly effective spin-enhancingfrictional engagement with the elastomer coating of a struck golf ball.Moreover, laser-etching, as combined with the mechanical milling used toform the first textured surface pattern (i.e., the micro-grooves 20),allows the value of R_(t) to be controlled quite precisely, and itreduces the dispersion of the values of R_(a), thereby allowing thevalue of R_(a) achieved by milling the micro-grooves 20 to assume anaverage value closer to the above-noted maximum permitted value. Laseretching also, by its nature, constitutes a localized heat treatingoperation. Thus, the regions structurally affected by the laser etchingprocess, i.e. the textured surface treatment regions 22, also constitutecoterminous heat-treated regions.

Alternative, or additional, processes for forming the textured surfacetreatment regions 22, which may achieve one or more of the aboveadvantages, include chemical etching, local media blasting (e.g. peeningor sandblasting), local oxidizing or other chemical roughening process,micro-milling, or local coating of the striking face 16 with a roughmaterial.

Referring to FIG. 8, an exemplary process 101 for forming the strikingface texture of FIG. 1 is shown. FIGS. 9-12 illustrate the club head 10after performance of the steps of the process 101 shown in FIG. 8. Ineach of FIGS. 9-12, the club head 10 is oriented such that the strikingface plane 56 coincides with the plane of the paper. The relative orderof the various steps of the process 101 is for purposes ofexemplification. One of ordinary skill in the art would appreciate that,unless indicated otherwise, various steps of the process 101 may beomitted, or the relative order of such steps may be altered withoutdeparting from the spirit and scope of the invention.

In step 102, a club head body is cast. In alternative embodiments, amain body is formed by forging and/or machining. Once formed, in step104, the club head body optionally undergoes a heat treatment process,whereby the club head body is case-hardened. Alternatively, or inaddition, the club head body is cold-worked or otherwise forged to moreadvantageously tailor the body's material properties.

Next, in step 106, the main body is optionally polished by means of asandblasting process (or other media blasting process). This step 106helps to remove any burrs or flashing that may have resulting from thecasting operation. In addition, the sandblasting process provides afoundation for an aesthetically pleasing final product.

Once sandblasted, in step 108, the main body undergoes a preliminarymilling operation particularly directed at the striking face 16. Thepreliminary milling operation is preferably carried out using a machinebit, feed rate, and spin rate such that a resulting roughness value,e.g. R_(a) value, is relatively low (e.g. an R_(a) value less than0.0033 mm or 130 μin.). In practical terms, this process is carried outas to preferably not result in any visually discernible ridges (e.g.using a cutting bit having a profile of a sufficiently high radius ofcurvature). In this manner, further texture-enhancing processes mayeffect a final striking face 16 having metrological properties closer totarget and more consistent from sample to sample.

After the preliminary milling operation of step 108, the striking face16 is milled under a different set of machining parameters to provide amilled surface having different visual and tactual characteristics, e.g.to produce the micro-grooves 20 discussed above, in step 110. FIG. 9shows the striking face 16 after the micro-grooves 20 have been formedby mechanical milling, optionally using CNC, to create the firsttextured surface pattern 19. In alternative embodiments, an arcuateridge pattern is stamped into the striking face 16 of the club headbody. In the illustrated exemplary embodiment, the first texturedsurface pattern 19 comprises a plurality of closely-spaced,substantially parallel, arcuate micro-grooves 20 that extend oversubstantially all of the striking face 16, as defined above. In aparticular example, the micro-grooves 20 produced by this step arespaced (from center to center) by a distance preferably no more thanabout 1.0 mm (0.04 in.), more preferably within the range of about 0.25mm (0.01 in.) to about 1.0 mm (0.04 in.), and even more preferably equalto about 0.6 mm (0.024 in.). Also, after step 110, the club headstriking face 16 preferably has an R_(a) value no less than about 0.0027mm (110 μin.), more preferably within the range of about 0.0030 mm (120μin.) and 0.0043 mm (170 μin.), and even more preferably equal to about0.0032 mm (125 μin.). Additionally, or alternatively, the striking face16, in this intermediate state, has an R_(t) value of about 0.014 mm(550 μin.).

In the embodiments discussed above, the second textured surface patternis superimposed on the first textured surface pattern 19. It is to beunderstood, however, that in other embodiments the first texturedsurface pattern may have other shapes and configurations. It is to beunderstood that the above-described principles also will apply to suchother embodiments.

With reference again to FIG. 8 and also to FIGS. 13-13D, an additionalembodiment of a first textured surface pattern 219 is shown. Theillustrated first textured surface pattern 219 comprises firstmicro-grooves 20 formed by the texture-generating face milling operation110 (see FIG. 8). Such micro-grooves 20 are arranged in a first millingpattern (also referred to as a first micro-groove pattern), as discussedabove. As shown, the first micro-grooves 20 are substantially parallelto each other. For example, one of ordinary skill in the art wouldappreciate that such arcuate grooves, when formed by a conventionalmilling process, will tend to slightly converge in the heelward andtoeward directions. After the first micro-grooves 20 are formed, asecond texture-generating face milling operation 130 (FIG. 8) can beperformed in which a plurality of second micro-grooves 220 are milledinto the striking face 16. The second micro-grooves 220 preferably aremilled in accordance with in a second milling pattern (also referred toas a second micro-groove pattern), which is superimposed on the firstmilling pattern to form the first textured surface pattern 219.

The second micro-grooves 220 of the second milling pattern preferablyare arranged in a pattern of generally parallel, arcuate lines. Forexample, one of ordinary skill in the art would appreciate that sucharcuate grooves, when formed by a conventional milling process, willtend to slightly converge in the heelward and toeward directions. InFIG. 13A, the score lines 18 are shown in phantom to indicate where theywill be positioned when eventually applied, and as shown the first andsecond micro-grooves 20, 220 are arranged so as to intersect the scorelines 18. Preferably, the score lines 18 are formed at step 112 aftermilling of the first and second micro-grooves 20, 220. As in theembodiment shown in FIG. 1, the score lines 18 of the club head 10 shownin FIGS. 13-13D preferably have a depth no less than 0.10 mm and areotherwise dimensioned to conform to USGA regulations. FIG. 13D shows acompleted golf club head 10 having the score lines 18 as well as thefirst and second micro-grooves 20, 220.

Continuing with reference to FIGS. 13-13D, the second micro-grooves 220preferably are formed by precision mechanical milling (e.g., CNCmilling), like the first micro-grooves 20. Also, preferably the secondmicro-grooves 220 are parallel to the first micro-grooves 20, and thusare convex relative to a virtual ground plane (i.e. form “frowns” whenthe club head is oriented in an address position) and have substantiallythe same radii of curvature. However, in alternative embodiments,micro-grooves 20 and/or micro-grooves 220 are concave relative to thevirtual ground place (i.e. form “smiles” when the club head is orientedin an address position). In the illustrated embodiment, adjacent secondmicro-grooves 220 are spaced farther apart from one another than areadjacent first micro-grooves 20. Thus, more than one, and preferably aplurality, of the first micro-grooves 20 are disposed between adjacentsecond micro-grooves 220. In the illustrated embodiment three firstmicro-grooves 20 are disposed between adjacent second micro-grooves 220.

With continued reference to FIGS. 13-13D, in the illustrated embodiment,the second micro-grooves 220 are generally wider and deeper than thefirst micro-grooves 20. In one preferred embodiment, the secondmicro-grooves 220 are formed using the same or a similarly-shapedmilling bit as was used to form the first micro-grooves. As such, thesecond micro-grooves 220 have a profile radius that is the same as thatof the first micro-grooves 20. When forming the second micro-grooves220, however, the milling bit is set for a slightly deeper cut andhigher feed rate than was used when forming the first micro-grooves 20.This results in forming second micro-grooves 220 that are deeper thanthe first micro-grooves 20 and adjacent second micro-grooves 220 beingspaced farther away from one another than are adjacent firstmicro-grooves 20. Also, the passing of the milling bit in the secondmilling process 130 results in removal of portions of asperities formedbetween first micro-grooves 20. This is shown in the roughness curvedepicted in FIG. 13C. Note that second micro-grooves 220 are generallydefined by asperity surface of first micro-grooves 20 in addition tosurfaces formed by the second mill pass 130. The result is secondmicro-grooves 220 having a width equal to about twice the width of thefirst micro-grooves. In some embodiments second micro-grooves 220 arespaced (from center to center) by a distance preferably no more thanabout 0.25 in., more preferably within the range of about 0.1-0.2 in.,and even more preferably about 0.14 in.

As discussed above, preferably the second micro-grooves 220 are deeperthan the first micro-grooves 20. For example, in some embodiments thedepth d₂ of the second micro-grooves 220 is 1.1-3 times the depth d ofthe first micro-grooves 20. More preferably depth d₂ is 1.2-2 times, andmost preferably 1.5-1.7 times depth d. Specifically, with reference toFIG. 13C, the first micro-grooves 20 preferably have an average depthbetween 300 and 600 micro-inches, more preferably between 400 and 550micro-inches, and most preferably equal to about 500 micro-inches (e.g.exemplary depth d is about 490 micro-inches). The second micro-groovespreferably have an average depth greater than the average depth of thefirst micro-grooves, more preferably between 400 and 700 micro-inches,even more preferably between 500 and 700 micro-inches, and mostpreferably equal to about 600 micro-inches (e.g. exemplary depth d2 isabout 600 micro-inches).

In some embodiments the average width of the second micro-grooves 220 isselected to be a whole number multiple of the average width of the firstmicro-grooves. For example, in the illustrated embodiment, as shown inFIG. 13C, second micro-grooves 220 have removed asperities previouslyforming edges of first micro-grooves 20. The result is secondmicro-groove widths that are about twice the first micro-groove widths.E.g., the exemplary first micro-groove width w₂ is about 0.032 in. Incontrast, a width w₃ of a second micro-groove 220 is about 0.060 in.

It is to be understood that, in further embodiments, the second millingpattern may not be so similar to the first milling pattern. For example,in some embodiments, the second micro-grooves 220 may not be parallel tothe first micro-grooves 20. For example, in contrast to firstmicro-grooves 20, second micro-grooves may have different radii ofcurvature, may be concave or convex relative to the virtual ground planeor relative to the virtual vertical planes 74, 76, may have widths thatare not whole number multiples of the widths of the first micro-grooves,may be thinner and/or shallower than the first micro-grooves 20, may beformed using a different milling bit and thus have a different profileradius than the first micro-grooves 20, and such.

Further, in other embodiments the first and second micro-grooves may beformed by procedures other than milling. For example, in someembodiments a first textured surface pattern 219, made up of a secondmicro-groove pattern superimposed on a first micro-groove pattern, canbe stamped into the striking face 16 of the club head body.

As with the embodiments discussed above in connection with FIGS. 1-12,the first textured surface pattern 219 as illustrated in FIGS. 13-13Dcan cover at least the central region 68 of the striking face, andpreferably extends at least partly into the toe region 78. Morepreferably, the first textured surface pattern extends at least partlyinto both the toe region 78 and the heel region 86. Preferably, thefirst textured pattern extends toward the toe portion past the uppermostpoint 82 of the club head 10 (see FIG. 2). In some embodiments, thefirst textured pattern covers the majority, and in some cases theentirety, of the toe region 78 of the striking face 16. Alternatively,or in addition, the first textured surface pattern can cover theentirety of the striking face 16 of the club head 10.

With reference next to FIG. 14, in another embodiment, the firsttextured surface pattern 219 may cover the central region 68 of thestriking face, but does not extend substantially into the toe region 78.Similarly, in other embodiments the extent of the first textured surfacepattern may be limited to, for example, the central region 68, and notextend substantially into one or both of the heel region 68 and toeregion 78.

Referring next to FIGS. 8 and 15-15B, in another embodiment, after thesecond texture-generating face milling operation 130 is completed, athird texture-generating face milling operation 140 can be performed inwhich a plurality of third micro-grooves 320 are milled into thestriking face 16. The third micro-grooves 320 preferably are milled in athird milling pattern (also referred to as a third micro-groovepattern), which is superimposed on the first and second milling patternsto form another embodiment of first textured surface pattern 319. Asshown in FIGS. 15A and 15D, score lines 18 can be formed on the strikingface 16 in addition to the micro-grooves 20, 220, 320. Further texturedsurface treatment regions 22 can also be formed on the striking face 16.

In the illustrated embodiment, the third micro-grooves 320 of the thirdmilling pattern are arranged in a pattern of parallel, arcuate linesthat substantially mirror the second micro-grooves 220 of the secondmilling pattern. More specifically, the third milling pattern isidentical to the second milling pattern, but rotated 180° so as to beconcave relative to the virtual ground plane. For example, the thirdmicro-grooves 320 have the same depth, width and spacing as the secondmicro-grooves 220, and even have the same arcuate shape (e.g., sameradii of curvature) except for the 180° rotation. The thirdmicro-grooves 320 can even be formed using the same or asimilarly-shaped milling bit as was used to form the secondmicro-grooves 220 and/or first micro-grooves 20.

With specific reference to FIGS. 15B and 15C, the third micro-grooves320 intersect the first and second micro-grooves 20, 220. The crosssectional view that is depicted in FIG. 15C is taken at a location (line15C-15C of FIG. 15B) at which the third micro-grooves 320 intersect andare perfectly aligned with the second micro-grooves 220. As can be seenby close review of FIG. 15B, however, such is not always the case alongthe striking surface.

In the embodiment illustrated in FIGS. 15-15B, the spacing betweenadjacent third micro-grooves 320 is the same as the spacing betweensecond micro-grooves 220. Similarly, due to their arcuate nature, eachof the first and second micro-grooves 20, 220 has an apex defined as thehighest point of the particular micro-groove along the striking face 16,and each of the third micro-grooves 320 has an apex defined as thelowest point of the particular micro-groove along the striking face 16.In the illustrated embodiment, the apexes of the second and thirdmicro-grooves 220, 320 are not aligned, and instead are spaced apartfrom one another so as not to intersect one another. In otherembodiments, apexes of the second and third micro-grooves 220, 320 canbe aligned with one another. In still further embodiments such apexescan partially overlap one another but not be fully aligned.

Preferably, each of the depth, width, and spacing of the secondmicro-grooves 220 is greater than the depth, width and spacing of thefirst micro-grooves 20, and each of the depth, width and spacing of thethird micro-grooves 320 is no less than the depth, width and spacing ofthe second micro-grooves 220. In the illustrated embodiment the secondand third micro-grooves 220, 320 have the same depth, width and spacing,maintaining the same milling depth, and feed rate as was used to formthe second micro-grooves 220. In the illustrated embodiment each of thefirst, second and third micro-grooves 20, 220, 320 also havesubstantially the same radius of curvature. In other embodiments thethird micro-grooves are greater than the second micro-grooves in one ormore of the depth, width and/or spacing. Additionally, the thirdmicro-grooves can be formed using a different milling bit than is usedto form either of the first and second micro-grooves, and thus may havea different profile.

In further embodiments, the third micro-groove pattern may have a shapestrikingly different than either the first or second micro-groovepattern. For example, the third micro-grooves may have centers ofcurvature that are offset more or less than 180° relative to the centersof curvature of the first and/or second micro-grooves. As such, thethird micro-grooves may be concave or convex relative to a plane otherthan the virtual ground plane. Also, the third micro-grooves may haveradii of curvature that are substantially different from the radii ofcurvature of the first and/or second micro-grooves.

In yet other embodiments the first, second and/or third micro-groovesmay be formed by procedures other than milling, such as, for example,stamping. Also, it is to be understood that other embodiments of thefirst textured surface pattern may have more than three micro-groovepatterns, such as having four, five or more micro-groove patterns. Insuch embodiments, all, some, or none of the micro-groove patterns mayshare one or more characteristics such as concavity/convexity, radius ofcurvature, depth, width, spacing, profile radius or the like.

In still another embodiment of the first textured surface pattern, onlythe second and third micro-groove patterns as discussed herein areformed on the striking face 16, and not the first micro-groove pattern.In one such embodiment, then, the overlaid second and third micro-groovepatterns are 180° opposite to one another.

Yet further, as with embodiments discussed above, the first texturedsurface pattern, regardless of whether it is made up of two, three ormore micro-groove patterns, can cover at least the central region 68 ofthe striking face, and preferably extends at least partly into the toeregion 78. More preferably, the first textured surface pattern extendsat least partly into both the toe region 78 and the heel region 86.Preferably, the first textured pattern extends toward the toe portionpast the uppermost point 82 of the club head 10 (see FIG. 2). In someembodiments, the first textured pattern covers the majority, and in somecases the entirety, of the toe region 78 of the striking face 16.Alternatively, or in addition, the first textured surface pattern cancover the entirety of the striking face 16 of the club head 10. Further,in some embodiments the first textured surface pattern may cover thecentral region 68 of the striking face, but not extend substantiallyinto the toe region 78 (similar to the embodiment illustrated in FIG.14). In other embodiments the extent of the first textured surfacepattern may be limited to, for example, the central region 68, and notextend substantially into one or both of the heel region 68 and toeregion 78.

As noted previously, the dimensions of the first and secondmicro-grooves 20, 220 and the spacing between them will have asignificant effect on the value of R_(a) of the striking face. Thus,these dimensional parameters must be selected so that the maximumpermitted value of R_(a) noted above is not exceeded. However, becauseof normal surface variation and machine tolerances, a sample pool ofclub heads having micro-grooves intended to effect a specific targetsurface roughness R_(a) value may likely effect surface roughness R_(a)values dispersed about a range. Consequently, as a practical matter, thefirst textured surface pattern is preferably selected to produce anaverage value of R_(a) close to, but still somewhat less than, thedesired optimal value of R_(a). Likewise, the first textured surfacepattern also produces a first value of R_(t), (which may be termed“R_(t1)”), that may advantageously be somewhat less than the desiredoptimum value of R_(t).

In some embodiments, an additional sandblasting operation is carried outin step 122. It may be advantageous to treat the striking face byconventional sandblasting, preferably immediately after the mechanicalmilling steps (steps 108 and 110, and optionally 130 and/or 140).Sandblasting may be performed for a variety of reasons, such asproviding a particular aesthetic appearance, and deburring and cleaningthe striking face after the milling step is performed. There are dataindicating that sandblasting may increase the value of R_(t), thusrequiring a corresponding adjustment of parameters used in the laseretching step to assure that the maximum permitted value of thisparameter is not exceeded. After such sandblasting, these roughnessvalues were increased by about 0.00013 mm to 0.00026 mm (5 to 10 μin.),preferably to about 0.0033 mm (130 μin.) (R_(a)) and about 0.018 mm (725μin.) (R_(t)). Subsequent polishing may be carried out to more sharplydefine the edges of the region of the striking face 16 occupied by thearcuate micro-grooves 20. In some embodiments, as shown, this firsttexture region is cut off sharply, forming a vertical boundary,proximate the heel portion 12 of the club head 10.

Next, the score lines 18 are formed on the striking face 16, forming anintermediate club head body configuration as shown in FIG. 10. Inalternative embodiments, the score lines 18 are integrally cast into themain body as a whole. In other embodiments, the scorelines 18 arestamped. However, preferably, the score lines 18 are formed by milling,optionally spin-milling. This method is advantageous in its precision.Preferably, the formation of the score lines 18 occurs subsequent to theformation of the milled first texture pattern 19, 219, 319. In thismanner, greater consistency in roughness may be achieved as the millingbit described above may be applied with even pressure throughout.Further, the score lines 18 may be formed with greater precision andmore sharply-defined edges.

In some embodiments, after the score lines 18 are formed, the club head10, or just the striking face 16, may optionally be plated or coatedwith a metallic layer, or treated chemically or thermally. Suchtreatments are well-known, and may enhance the aesthetic qualities ofthe club, and/or one or more utilitarian aspects of the club (such asdurability or rust-resistance). For example, in some embodiments, instep 114, the club head 10 is nickel-plated and optionally subsequentlychrome-plated in step 116. Such plating enhances the rust-resistancecharacteristics of the club head. Further, such plating improves theaesthetic quality of the club head 10, and it may serve as a substratefor any future laser etching process. Plating selection is also believedto have an effect on the visual and/or textural characteristics ofsubsequently-formed laser-etched regions superimposed thereon.Optionally, subsequent to the nickel- and chrome-plating steps 114 and116, the striking face undergoes a physical vapor deposition (“PVD”herein) process. Preferably, the PVD operation results in a layer thatcomprises either a pure metal or a metal/non-metal compound. Preferably,the PVD-formed layer comprises a metal comprising at least one of:vanadium, chromium, zirconium, titanium, niobium, molybdenum, hafnium,tantalum, and tungsten. More preferably, the PVD-applied layer ischaracterized as a nitride, a carbide, an oxide, or a carbonitride. Forexample, a layer of any of zirconium nitride, chromium nitride, andtitanium carbide may be applied, depending on the desired visual effect(e.g. color) and/or material properties. Preferably, the PVD operationresults in a layer of titanium carbide. This process enhances theaesthetic quality of the club head 10, while also increasing thedurability of the striking face 16.

Next, a laser etching operation 120 is carried out, thus forming thetextured surface treatment regions 22. For example, FIGS. 1, 11, and 12show an embodiment of the striking face 16 after the textured surfacetreatment regions 22 have been formed. As shown, the textured surfacetreatment regions 22 create the second textured surface pattern,superimposed on the first textured surface pattern 19. For the sake ofconvenience this discussion is in the context of the embodiment of thefirst textured surface pattern 19 as illustrated in FIGS. 1-12. It is tobe understood, however, that the principles discussed herein will applyto other embodiments, such as the embodiments of the first texturedsurface pattern 219, 319 as illustrated in FIGS. 13-15D. In fact, FIG.15D depicts a completed golf club having textured surface treatmentregions 22 in addition to micro-grooves 20, 220, 320 and score lines 18.

In the illustrated exemplary embodiment, two or more substantiallyparallel textured surface treatment regions 22 are formed between eachadjacent pair of score lines 18, and several more textured surfacetreatment regions 22 are advantageously formed both above an uppermostscore line 18 a and below a lowermost score line 18 b (see FIGS. 11 and12). The textured surface treatment regions 22 advantageously occupy atleast approximately the portion of the striking face 16 that is occupiedby the grid of score lines 18, i.e., the central region 68.Advantageously, the textured surface treatment regions 22 may extendfarther toward the heel portion 12 than some or all of the score lines18. The laser etching operation 120 is preferably carried out after thescore line forming process 112 in part such that the score lines 18provide a basis for properly and efficiently aligning the feed directionof the laser.

After laser etching, the value of R_(a) may not be appreciablyincreased, but other benefits are suggested by empirical data of thecombined effect of the laser-etched regions and the mechanically milledregions. For example, this combination appears to provide a low-costresultant texture that bears a narrower margin of error of roughnessover a sample set as compared with mechanical milling alone. Because ofa smaller tolerance window, the target R_(a) can be raised closer to themaximum under USGA regulations. Preferably, the final striking facesurface roughness (R_(a)) is within the range of 0.0030 mm (120 μin.)and 0.0047 mm (185 μin.). Also, the value of R_(t) was increased to asmuch as about 0.024 mm (950 μin.), thus providing for consistentlyapproaching the maximum R_(t) limit set by the USGA.

In the exemplary embodiment, each of the textured surface treatmentregions 22 is formed as a series of etched lines by a pulsed laser,preferably with a wavelength within the range of about 900 nm to about1200 nm, more preferably within the range of about 1000 nm to about 1100nm, and most preferably equal to about 1064 nm. Each of the etched linesis preferably formed by a first pass of the laser head in a firstdirection, and a second pass in the opposite direction. The power, pulserate, and linear speed of the laser head will depend on the particularsurface treatment of the striking face. For example, if the strikingface 16 is subjected to physical vapor deposition (PVD) (e.g. in step118), the first pass may be performed at a pulse rate of 20 KHz, a powerof about 4.2 KW, and a linear speed of 800 mm/sec, while the second passmay be performed at a pulse rate of 10 KHz, a power of about 3.5 KW, anda linear speed of 180 mm/sec. For a chrome-plated striking face, thefirst pass may be performed at a pulse rate of 10 KHz, a power of about3.5 KW, and a linear speed of 180 mm/sec, while the second pass may beperformed at a pulse rate of 20 KHz, a power of about 4.2 KW, and alinear speed of 800 mm/sec. Using these laser settings, a value of R_(t)very close to 0.025 mm (1000 μin.) can be achieved (e.g., about 950 μin.or 0.024 mm) with the etched lines having the following physicalparameters (and assuming a milled texture in accordance with the designparameters described above):

Width of the laser-etched region created by each pass: 0.11 mm Totallaser-etched region width: 0.36 mm Distance between adjacentlaser-etched regions: 0.67 mm

It will be understood that lasers with different operational parameters(e.g., wavelength, power, pulse rate, and/or linear head speed) fromthose described above in the exemplary embodiment may be used to achievevalues of R_(t) that are close to, but that do not exceed, theabove-noted maximum permitted value. Also, the distance between adjacentlaser-etched regions corresponds to the distance S of FIG. 5A.

The above description presents the best mode contemplated for carryingout the present invention, and of the manner and process of making andusing it, in such full, clear, concise, and exact terms as to enable anyperson skilled in the art to which it pertains to make and use thisinvention. This invention is, however, susceptible to modifications andalternate constructions from that discussed above that are fullyequivalent. Consequently, this invention is not limited to theparticular embodiments disclosed. On the contrary, this invention coversall modifications and alternate constructions coming within the spiritand scope of the invention as generally expressed by the followingclaims, which particularly point out and distinctly claim the subjectmatter of the invention.

What is claimed is:
 1. A golf club head comprising: a heel portion; atoe portion opposite the heel portion; a loft angle of at least 18°; anda striking face having a surface roughness Ra within a range of about0.0030 mm (120 μin) and about 0.0047 mm (185 μin), the striking faceincluding: a plurality of score lines each having an average depth noless than about 0.10 mm; a first micro-groove pattern comprising aplurality of first micro-grooves, each of the first micro-grooves havinga first average depth no greater than about 0.025 mm and a first averagewidth, the first micro-grooves being substantially parallel to oneanother; and a second micro-groove pattern comprising a plurality ofsecond micro-grooves, each of the second micro-grooves having a secondaverage depth no greater than about 0.025 mm and a second average widthdifferent than the first average width, the second micro-groves beingsubstantially parallel to one another, wherein the second micro-groovepattern is overlaid onto the first micro-groove pattern.
 2. A golf clubhead as in claim 1, wherein the second average width is greater than thefirst average width.
 3. A golf club head as in claim 1, wherein thesecond micro-grooves are parallel to the first micro-grooves.
 4. A golfclub head as in claim 1, wherein, when the golf club head is oriented ina reference position, the first micro-grooves and the secondmicro-grooves form upwardly convex paths.
 5. A golf club head as inclaim 1, wherein the second micro-grooves are spaced from each other bya distance no less than about 0.2 in.
 6. A golf club head as in claim 1,wherein the striking face further comprises a plurality of heat-treatedregions.
 7. A golf club head as in claim 6, wherein the plurality ofheat-treated regions comprises laser-etched regions.
 8. A golf club headas in claim 6, wherein each of the heat-treated regions extends along agenerally linear path.
 9. A golf club head comprising: a heel portion; atoe portion opposite the heel portion; a loft angle of at least 18°; anda striking face having a surface roughness Ra within a range of about0.0030 mm (120 μin) and about 0.0047 mm (185 μin), the striking faceincluding: a plurality of score lines each having an average depth noless than about 0.10 mm; a first micro-groove pattern comprising aplurality of first micro-grooves, each of the first micro-grooves havinga first cross-sectional profile defining a first average depth nogreater than about 0.025 mm and a first average width, the firstmicro-grooves being substantially parallel to one another; and a secondmicro-groove pattern comprising a plurality of second micro-grooves,each of the second micro-grooves having a second cross-sectional profiledefining a second average depth no greater than about 0.025 mm and asecond average width, the second micro-grooves being substantiallyparallel to one another, wherein the second micro-groove pattern isoverlaid onto the first micro-groove pattern; and wherein the firstcross-sectional profile is different from the second cross-sectionalprofile.
 10. A golf club head as in claim 9, wherein the striking facefurther comprises a plurality of heat-treated regions.
 11. A golf clubhead as in claim 10, wherein the plurality of heat-treated regionscomprises laser-etched regions.
 12. A golf club head as in claim 10,wherein each of the heat-treated regions extends along a generallylinear path.